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Causal
Agent:
Burkholderia solanacearum
(synonym: Pseudomonas solanacearum) (synonym: Ralstonia
solanacearum)
At
least three races have been reported.
Distribution:
Worldwide (subtropical and tropical areas)
Symptoms:
Symptoms begin as drooping of the lower leaves followed soon after by
wilting of the entire plant. No foliar yellowing is associated with this
wilt disease. When the stem is cut a slimy, gray exudate oozes from the
cut end. A longitudinal section of the stem reveals a yellow to light
brown vascular discoloration which later turns darker brown and/or
hollow as the disease progresses. A quick aid to diagnosis is to place a
freshly cut stem piece in water. A white, milky stream of bacteria will
ooze from the cut stem.
Conditions for Disease Development:
This bacterium has a host range of greater than 200 plant species which
it can infect and survive on. It can also survive in the soil where it
infects roots through natural wounds caused by the formation of
secondary roots, or through wounds caused by transplanting, cultivation
practices or nematode feeding. Chewing insects may also transmit the
bacterium. It can be spread in irrigation water, in soil on cultivation
equipment and in diseased transplants. Warm (29-35°C, 84-95°F) weather
and high soil moisture levels favor the development of this disease.
Control: The use of disease free transplants, soil fumigation, weed control and
crop rotation can all reduce the incidence of this disease. Grafting onto
resistant rootstocks or using tolerant varieties can be effective in
minimizing losses from bacterial wilt.
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Wilting
symptoms in the field.
Cut
stem showing
pith discoloration.
 
Cut
stem showing
pith
Testing for
Bacterial strea-
discoloration.
bacterial strea- ming from a
ming from a cut stem.
cut stem.
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